DOI QR코드

DOI QR Code

Field-Curvature Correction According to the Curvature of a CMOS Image-Sensor Using Air-Gap Optimization

Kwon, Jong-Hoon;Rhee, Hyug-Gyo;Ghim, Young-Sik;Lee, Yun-Woo

  • Received : 2015.10.02
  • Accepted : 2015.10.28
  • Published : 2015.12.25

Abstract

Lens designers generally refer to flat image fields and attempt to minimize the field curvature. Present-day CMOS image sensors for mobile phone cameras, however, are not flat, but curved. Sometimes it is necessary to generate an intentional field curvature according to the degree and direction of the CMOS image-sensor’s curvature. This paper presents the degree of curvature of a CMOS image sensor measured using an interferometer, and proposes an effective compensation method that minimizes the net field curvature through optimizing the air gap between lens elements, which is demonstrated using simulations and experiments.

Keywords

Phone camera lens module;Field curvature compensation;Air gap optimization

References

  1. J. H. Bruning, “Phase shifting interferometers,” in Optical Shop Testing, 2nd ed. (Wiley, New York, USA, 1992), Chapter 14.
  2. P. de Groot, “Derivation of algorithms for phase-shifting interferometry using the concept of a data-sampling window,” Appl. Opt. 34, 4723-4730 (1995). https://doi.org/10.1364/AO.34.004723
  3. K. Freischlad and C. L. Koliopoulos, “Fourier description of digital phase measuring interferometry,” J. Opt. Soc. Am. A 7, 542-551 (1990). https://doi.org/10.1364/JOSAA.7.000542
  4. J. C. Wyant, “Interferometric optical metrology: basic principles and new systems,” Laser Focus 18, 65-71 (1982).
  5. J. W. Goodman, “Analog optical information processing,” in Introduction to Fourier Optics, 2nd ed. (McGraw-Hill, Singapore, 1996), Chapter 8.
  6. P. D. Burn, “Slanted-edge MTF for digital camera and scanner analysis,” in Proc. IS&T 2000 PICS Conference (Portland, OR, USA, March 2000), pp. 135-138.
  7. M. Marchywka and D. G. Socker, “Modulation transfer function measurement technique for small-pixel detectors,” Appl. Opt. 31, 7198-7213 (1992). https://doi.org/10.1364/AO.31.007198
  8. T. Kolehmainen and M. Ojala, “Random target method for fast MTF inspection,” Opt. Express 12, 2610-2615 (2004). https://doi.org/10.1364/OPEX.12.002610
  9. M. Yamamoto and S. Horiuchi, “Simulation of modulation transfer function using a rendering method,” Opt. Express 21, 7373-7383 (2013). https://doi.org/10.1364/OE.21.007373
  10. R. E. Fischer and T. G. Biljana, “Computer performance evaluation,” in Optical System Design (McGraw Hill, New York, USA, 2000), Chapter 10.
  11. M. Born and E. Wolf, “Geometrical theory of optical imaging,” in Principles of Optics, 2nd ed. (Pergamon Press, New York, USA, 1989), Chapter 4.
  12. ISO12233:2000, “Photography-electronic still-picture camerasresolution measurements,” 7-16 (International Standard, Geneva, 2000).
  13. www.trioptics.com/knowledge-base/mtf-and-image-quality, MTF & Image Quality & Image Master HR Product Information.
  14. S. Kim, H. S. Yang, Y. W. Lee, and S. W. Kim, “Merit function regression method for efficient alignment control of two-mirror optical system,” Opt. Express 15, 5059-5068 (2007). https://doi.org/10.1364/OE.15.005059
  15. www.zemax.com, Optical System Design Tutorials - Optimization & Tolerance
  16. W. Wallin, “The control of Petzval curvature,” J. Opt. Soc. Am 41, 1029-1032 (1951). https://doi.org/10.1364/JOSA.41.001029
  17. D. Malacara and S. L. DeVore, “Interferogram evaluation and wavefront fitting,” in Optical Shop Testing, 2nd ed. (Wiley, New York, USA, 1992), Chapter 13.

Cited by

  1. Performance Evaluation of MTF Peak Detection Methods by a Statistical Analysis for Phone Camera Modules vol.20, pp.1, 2016, https://doi.org/10.3807/JOSK.2016.20.1.150